hit to lead 1

explain the importance of solubility

important to run in vitro assays and in vivo deliver of the drug to determine drug absorption and bioavailability, target is >100 microM

describe lipophilicity/hydrophilicity balance

balance is required to ensure sufficinet membrane permeability without excessive fat deposition or toxicty, target is 0-3

describe microsomal toxicity

this assay measures compound clearance by the liver enzymes to give an idea of how quickly will the drug be cleared in vivo

target < 30 microL/ min mg protein

describe cyp450 inhibition

cyp450 enzymes do phase 1 metabolism by introducing polar groups to increase water solubility, its inhibition can lead to drug accumulation and toxicity

target >10 microM

describe caco-2 permeability

it measures drug's ability to cross intestinal epithelial membrane, important for gut absorption

target > 1x10^-6 cm-1

describe MDCK permeability

evaulates the impact of efflux pumps like p-glycoprotein, which can pump the drug out and reduce absorption

target < 10x10^-6 cm-1

describe HepG2 hepatotoxicity screening

assess liver specific toxicity, target is 50x IC50 or EC50

describe cytotoxicity assays

check general cell toxicity in other tissues like heart, muscle, lung

what is the importance of heterocyclic core

function groups are arranged around flat, rigid, heteroaromatic, small core that allows rapid synthesis of analogues, optimise Log P, solubility etc, template hopping to novel IP

6 membered ring- pyradine, quinolone

5 membered ring- imidazole,thiazole

fused system- purine, indole

saturated system- piperidine

what is the criteria to move hit to lead

reproducable in vitro efficacy, >100 fold selectivity for the target, favourable drug ADME properties, chemical tractability( simple synthetic pathway and commercially available starting material), patentable structure, no toxicity or mutagenicity

give an hit to lead example

hit started with a known protein kinase inhibitor as the core

lead optimization modified the core to create analogues and used x-ray crystallogrphy to identify binding sites founding Imatinib- myeloid leukemia

Describe how Caco-2 works

form a monolayer of 2 cells, in the apical side add the drug and allow the drug to cross through semi-permeable membrane, in the basal lateral side sample the drug and use LCMS or chromatogrpahy to determine the concentration between apical and basolateral, if a drug has high permeability then a high level of it has moved to basolateral side

What is bioavailability?

how mcuh of the drug actually reaches systemic circulation

describe the importance of plasma protein binding

high binding can affect dose, half-life and cause toxicity

FU (fraction unbound) >90 %

what is druggability DMPK assessment

A-absorption Caco-2 and MDCK

D- distribution plasma protein binding

M-metabolism CYP450, microsomal stability

E-excretion PK screening w urine analsys